The invention relates to a thermoplastic panel or piece having a flexible, resilient welded portion affixed thereto. The panel or piece of the present invention may be used in a variety of applications such as to provide sealing ends on thermoplastic panels or to create resiliently closeable passages in thermoplastic panels through which wires and other objects may be passed while maintaining an even surface appearance of the baseboard panel.
The present invention pertains generally to the field of thermoplastic constructions such as those in office furnishings and equipment, hospital and clinic furnishings, cafeteria furnishings, office partitions, etc.
Office furnishings and equipment, and the like, are often put into service in environments where there is exposure to impact and abrasion, such as through heavy foot traffic, hand contact, or exposure to things in motion, such as dollies, carts, tables and chairs, wheelchairs and hospital beds. Office furnishings and equipment, and the like, are often provided with baseboards, railings and other pieces to resist or absorb impacts and scuffing, as well as to present and maintain an even and neat appearance. It is also often the case that such furnishings use trim pieces, and the like, to provide a continuous covering or finish. However, such pieces must be produced so as to be securely incorporated into the balance of the furnishing piece, such as along the top or bottom of office partitions. Accordingly, it is desirable to be able to produce a trim piece or panel capable of secure incorporation into a furnishing piece.
To achieve these ends, it is often desirable to be able to take advantage of two or more plastic materials having different flexion and appearance qualities by combining them into an integral part. This is complicated by the fact that attempts to incorporate different materials require a secondary adhesion operation involving specialized adhesives or the injection molding of different polymers under conditions that may not allow the two materials to sufficiently adhere and/or may mar the surface or other aesthetic qualities of the part (such as through the application of heat and/or pressure).
It is also often desirable to be able to produce plastic composites capable of being used as sight and/or light barriers, as well as to produce products that present and maintain desirable aesthetic qualities. Also, in many instances, these pieces must be made to allow the passage of various electrical and signal transmissive wires, fiber optic cables, and the like, which are often necessary to operate office equipment such as telephones, computers, copiers, projectors, lights, etc.
To this end, panels normally have been provided with holes or gaps to allow wires and cables to be passed through. However, the various potential applications of baseboard panels, their arrangement and their working environments make it difficult to predict where wire/cable access will be needed, and the size and number of wires or cables to be passed through at a given location.
One of the ways of constructing a gapped baseboard panel is to extrude a relatively rigid panel of material such as a rigid PVC. These panels are then cut to a desired length and a relatively flexible polymeric material, such as a flexible PVC material, is adhered to the relatively rigid material through use of an adhesive, such as a cyanoacrylate adhesive, in a secondary hand operation.
There are several problems attendant to the use of such adhesives in hand operations. One problem is that of ventilation. The adhered pieces must normally be carefully stacked to provide sufficient curing and ventilation. Also, in the case of cyanoacrylate adhesives, the vapor issuing from the curing adhesive can form a white deposit on the finished pieces, often rendering them unacceptable to the manufacturing customer. Naturally, any gaseous emissions from curing adhesive may pose a health hazard to the operator. Additionally, another problem with the use of adhesives with PVCs relates to the plasticizers which migrate from the PVC into the adhesive. This softens the adhesive and causes loss of its cohesive strength.
The use of liquid adhesives in hand operations are also inefficient. Liquid adhesive can be spilled, requiring cleanup, and hand operations, even when carefully done, can lead to gaps in the alignment between the rigid and flexible portions. It is therefore more difficult to manufacture such pieces within required tolerances.
Finally, the use of liquid in hand operations must rely upon the operator to dispense the appropriate amount of adhesive uniformly to be sure that a strong bond is achieved. This is often difficult to do efficiently in repetitive operations.
Accordingly, it is desirable to be able to produce a baseboard panel which can accommodate, alternatively, the throughput of a small or great number of wires (or wires of a small or great diameter) or remain unused, while maintaining an even appearance and without the use of separable parts.
It is further an object of the present invention to produce a finishing panel with a strong and uniform bond across the interface between the rigid and flexible portions, while eliminating the environmental hazards, inefficiencies and product objections discussed above.
It is also an object of the present invention to provide an aperture covering for a piece or panel which is durable and resists the impact and flexion often occurring in high traffic environments, and the like.
In view of the present disclosure and/or through practice of the present invention, other advantages and the solutions to other problems may become apparent.
One embodiment of the invention is a method of vibrationally welding a relatively flexible polymeric material onto a surface of a relatively less flexible material, typically both thermoplastic materials, using radio frequency welding. As used herein, the term xe2x80x9crelatively flexiblexe2x80x9d may include, for instance, comparative references to the flexibility as between rigid and semi-rigid materials, rigid and flexible materials, semi-rigid materials and flexible materials, etc.
In this regard, the relatively flexible materials may include ethyl vinyl acetate (EVA), urethanes (such as thermoplastic polyurethanes), PVC-urethane alloys (such as those commercially available from Alpha Chemical and Plastics Corporation), flexible PVC, alloyed vinyls, thermoplastic rubbers (TPRs) and polyester elastomers, such as Hytrel(copyright) commercially available from DuPont(copyright). The relatively more flexible polymeric material may be selected from the group consisting of those preferably having a Shore A hardness in the range of from about 60 to about 95 according to ASTM method D-2240, most preferably in the range of from about 70 to about 80 according to ASTM method D-2240.
The relatively rigid polymeric material may be any extrudable material, such as those selected from the group consisting of rigid or semi-rigid PVC. Such materials may have a Shore D hardness of at least 65 according to ASTM method D-785, preferably in the range of from about 50 to about 90 according to ASTM method D-785, preferably in the range of from about 78 to about 82 according to ASTM method D-785.
A second embodiment of the invention includes vibrationally (ultrasonic) welding a coextruded polymeric material onto a surface of a relatively rigid or semi-rigid material, said coextruded polymeric material as used herein being a coextruded polymer having a relatively flexible side and a rigid or semi-rigid side and wherein the bonding occurs via ultrasonic welding of the overlapping rigid or semi-rigid side of the coextruded material with the surface of the rigid or semi-rigid material.
The present invention also includes a part such as that made in accordance with the methods described herein. Such a part generally comprises: (1) a relatively rigid piece (which may be adapted to be attached to a furnishing piece; typically a thermoplastic material), having an application surface; and (2) a portion of a material (also typically a thermoplastic material) being relatively more flexible than the relatively rigid material, and welded onto the application surface of said rigid piece; or (3) a portion of a coextruded material (also typically a thermoplastic material having a relatively more flexible and a more rigid side) and welded onto the application surface of said rigid piece.
It is preferred that the polymeric extrudate be a semi-rigid or rigid material, preferably PVC, and most preferably having a Shore D hardness in the range of from about 78 to about 82. An example of such a material is PVC Formulation 87256, commercially available from Geon Corporation.
An example of a urethane material which may be used in accordance with the present invention, is Pellethane(copyright), commercially available from Dow Chemical. An example of an ethylene-vinyl acetate copolymer which may be used in accordance with the present invention is ELVAX(copyright), commercially available from Dow Chemical.
The materials which may be used for the relatively rigid and relatively flexible portions may be as given above.
These and other objects of this invention will be evident when viewed in light of the drawings, detailed description, and appended claims.